Câu hỏi của lê trần minh quân

Question

2.Tìm x,y thuộc Z, biết

a)(x-2)(x+3)=15

b)(2x-1)(y-4)=-13

c)(x+3)chia hết cho x+1

Anh2Kar六 · Accepted Answer

c)$\Leftrightarrow$(x+1)+2 chia hết x+1
$\Rightarrow$2 chia hết x+1
$\Rightarrow$x+1 ∈ {1,-1,2,-2}
$\Rightarrow$x ∈ {0,-2,1,-3}

Câu trả lời:

c)$\Leftrightarrow$(x+1)+2 chia hết x+1
$\Rightarrow$2 chia hết x+1
$\Rightarrow$x+1 ∈ {1,-1,2,-2}
$\Rightarrow$x ∈ {0,-2,1,-3}

Trần Đặng Phan Vũ · Answer

c) $x+3⋮x+1$

$\Rightarrow x+1+2⋮x+1$

$\Rightarrow2⋮x+1$ ( vì $x+1⋮x+1$ )

$\Rightarrow x+1\in\text{Ư}_{\left(2\right)}$

$\text{Ư}_{\left(2\right)}=\text{ }\left\{1;-1;2;-2\right\}$

$x+1$	$1$	$-1$	$2$	$-2$
$x$	$0$	$-2$	$1$	$-3$

vậy................